Scientists hope DNA in water could be way to save rare fish

Species such as the Arctic char live in 14 water bodies in Maine, but nowhere else in the continental United States.

By Patrick WhittleAssociated Press

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University of Maine graduate student Brad Erdman holds an Artic char, left, and a brook trout, right, at Floods Pond near Otis in October. Scientists in Maine are in the middle of a project to use DNA to help preserve Arctic char, which are at the southern end of their range in the state. Mitch Paisker via Associated Press

Scientists in Maine are using DNA to try to preserve the remaining populations of a fish that lives in 14 lakes and ponds in the state and nowhere else in the continental United States.

The scientists are turning their eye to the Arctic char, which is a species of landlocked fish in Maine that has lived in the state for millennia and is prized by anglers. The char face threats such as invasive predators and a warming climate. They are also notoriously elusive, making them difficult for researchers to track.

Michael Kinnison, a professor of evolutionary applications at the University of Maine, and other scientists are working with the state to make sure the fish keep surviving. Kinnison is working on a project to collect “environmental DNA” from the water bodies where the fish live.

The project involves collecting water samples from the lakes and ponds where the fish are known to live, and studying DNA that they and other organisms shed, Kinnison said. It will provide vital information scientists can use to keep char populations stable, he said.

It’s also a much less invasive and time-consuming way than older methods, such as using nets, Kinnison said.

“If your only tool to count a species is a gillnet, and there’s not many, do you make the tough choice to risk killing the individuals to find them?” he said. “It’s a way to get an idea of where organisms are located and do it in a way that presents really no harm.”

Arctic char live at the top of the world, including in northern Canada and Alaska. They’re known to seafood lovers because they’re farmed for use as food. But to find one in the lower 48 states, an angler can only go to one of a group of remote, rural ponds and lakes in Maine, some of which are barely accessible to humans.

The project to collect their DNA in Maine launched in 2017, and is expected to continue through this summer, said Brad Erdman, a University of Maine ecology graduate student who is working on it. A local chapter of Trout Unlimited, an environmental nonprofit, is working on the project using grant money provided by the organization’s Embrace-A-Stream fund.

One of the biggest threats to the char is the presence of invasive rainbow smelt, a species of small fish that competes with char for food and are suspected of eating chars’ young. The char were the subject of a project to eradicate the smelt from Big Reed Pond in northern Piscataquis County to save the char’s population there. The Maine Department of Inland Fisheries and Wildlife confirmed in June 2017 that the char are spawning in the pond again.

Using environmental DNA can help make sure the smelt don’t gain a foothold in other bodies of water where the char live, said Francis Brautigam, director of fisheries for the state wildlife department. The smelt have been illegally introduced in Bald Mountain Pond in Somerset County, where char populations have dropped, and controlling the situation is a priority.